Linear actuated robotic packaging device and method

ABSTRACT

An end of arm tool that is capable of handling fragile items such as eggs that are packaged in containers (e.g., egg cartons) that require special handling is provided. The end of arm tool comprises pivotal clamps operated by sliding-contact linear actuators and return springs. A retractable gripper for placing divider sheets between packages in the cases may be disposed above the clamps and oriented 90 degrees from the clamps, so that the clamps and gripper may be attached to the same tool without either obstructing the operation of the other. In addition, a method of loading packages, and optionally divider sheets, into cases using the end of arm tool apparatus of the present invention is provided.

RELATED APPLICATIONS

This application is a continuation in part of U.S. application Ser. No. 12/217,545, filed Jul. 7, 2008, which in turn is a divisional of U.S. application Ser. No. 11/478,059, filed Jun. 29, 2006.

FIELD OF THE INVENTION

The present invention relates to an end of arm tool for a robotic arm which is suitable for placing packages into cases. Specifically, the present invention relates to an end of arm tool suitable for packing egg cartons into a shipper case.

BACKGROUND OF THE INVENTION

The use of robotic arms has been readily adopted across diverse industries because they increase efficiency in the production process and reduce labor costs. The widespread use of robotic arms is due largely to their versatility of performing different tasks. This versatility is accomplished by the use of end of arm tools (EOATs) that are specifically designed to perform specialized tasks. For example, robotic arms are used to perform complex operations that require the highest degree of accuracy and precision, such as the manufacturing of circuit boards or computer chips. In other industries, robotic arms have replaced manual labor for tasks that were traditionally performed manually by humans such as packing bottles into shipper cases, painting automobiles on the assembly line, and many other similar tasks. All these tasks can be performed by end of arm tools that have been specifically designed to perform a task such as painting cars on the assembly line, soldering transistors onto circuit boards, and loading bottles into shipper cases.

Despite the many uses of robotic arms, there is still a need to provide an end of arm tool that is capable of handling fragile items that require special handling such as eggs that are packaged in containers (e.g., egg cartons) which are then placed in shipper cases. Heretofore, packing cartons of eggs into shipper cases has remained a manual task.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, an end of arm tool comprises a plate having a top surface and a bottom surface. At least one clamp actuator is located on the bottom surface of the plate. The clamp actuator operates a clamp bar to which a plurality of clamp fingers is connected. A vacuum cup assembly is also located on the bottom surface of the plate.

In one embodiment of the present invention, the end of arm tool further comprises at least one release actuator located on the top surface of the plate that operates a pusher assembly located along the bottom surface of the plate.

In another aspect, the invention is an end of arm tool comprising gripping means for gripping a package by its top surface and clamping means for clamping the edges of the package. The end of arm tool may further comprise releasing means for releasing the package from the end of arm tool.

According to another aspect of the present invention, a method of packing cases is provided. The method comprises connecting an end of arm tool comprising a vacuum cup assembly and a plurality of clamp fingers to a robotic arm, and controlling the robotic arm to place the end of arm tool over a package so that the vacuum cup assembly makes contact with the top surface of the package. A vacuum is generated so that the vacuum cup assembly grips the top surface of the package. The clamp fingers are retracted to clamp the edges (e.g., the ends, or the ends and sides) of the package and the robotic arm is controlled to lift the package and carry the package to a case. The method further comprises moving the robotic arm into the case to place the package in the case, releasing the package, and moving the robotic arm out of the case.

In another aspect of the invention, a gripper is provided on the end of arm tool for picking up a divider sheet, such as a sheet of cardboard, and placing it in the case between layers or columns of cartons.

According to yet another aspect of the invention, a pivotal-clamp end of arm tool is provided. The pivotal-clamp end-of-arm-tool includes first and second generally opposed clamping members pivotally connected to a base about a first clamping axis and a second clamping axis, respectively, the first and second clamping axes being generally parallel to each other. First and second linear thrusters are mounted for linear movement relative to the base, the thrusters having contact ends configured to extend toward and press against contact surfaces of the first and second clamping members, respectively, to cause a clamping end of each of the first and second clamping members to pivot generally towards the clamping end of the other of the first and second clamping members. The contact ends of the thrusters may include generally convex, curved contact faces configured for sliding contact with the contact surfaces of the clamping members. This produces a clamping force for clamping a package between the first and second clamping ends.

In one embodiment, the tool includes a pusher mechanism adapted to push a package away from the clamping members in a direction transverse to a distance between the clamping members to release the package from the clamping members when the clamping members partially obstruct the movement of the package away from the clamping members. A pusher mechanism is not strictly necessary in the absence of vacuum retention means, but may be advantageous when the clamping members are restrained or prevented from fully opening, as when the tool is inserted into a narrow box. For example, in a preferred embodiment, the clamping members comprise retention lips adjacent their clamping ends, the retention lips being a portion of each clamping member turned inwardly toward the opposed clamping member, wherein a distance between the retention lips is shorter than a distance between the clamped ends of a clamped package, i.e., a clamped length of the package. To passively release the package, the clamping members must open so as to decrease the distance between the retention lips sufficiently so that the package may fall between them under its own weight. When the clamping members are restrained or prevented from opening this much, the package is still retained between the clamping members even when the clamping force has been removed. In such a case, a pusher mechanism is advantageously engaged to cause deflection in the partially obstructed package, the clamping members, or both, so that the partially obstructed package may pass between the retention lips.

Preferably, the tool includes first and second return springs configured to urge the contact surfaces of the first and second clamping members, respectively, to pivot toward and against the contact ends of the first and second thrusters, respectively, and to urge the first and second clamping ends apart from each other. This permits the tool to release a clamped package, while at the same time preparing to clamp another package, when the thrusters are retracted.

In one embodiment, the tool further includes third and fourth generally opposed clamping members pivotally connected to the base about a third clamping axis and a fourth clamping axis, respectively, the third and fourth clamping axes being generally parallel to each other and generally orthogonal to the first and second clamping axes. The third and fourth clamping members may be operated by third and fourth linear thrusters, similarly to the first and second clamping members. The first, second, third and fourth clamping members may be configured to clamp a group of adjacent packages simultaneously between the first and second clamping members and between the third and fourth clamping members. For example, three one-dozen packages may be arranged side-by-side in a row, and the first and second clamping members may clamp the opposite ends of each package, while at the same time the third and fourth clamping members clamp the outer side edges of the cartons at the ends of the row, thus clamping their inner side edges flush against the middle carton.

In still another embodiment of the invention, an end of arm tool comprising egg-carton clamping and divider-sheet gripping mechanisms is provided. The tool includes first and second clamping members movably mounted to generally opposite sides of a base for movement of generally opposed clamping portions of the first and second clamping members toward each other and into a clamping configuration for clamping a package between the clamping portions and for movement of the clamping portions away from each other and out of the clamping configuration to release a package clamped between the clamping portions. The clamping members are adapted to clamp a horizontally oriented package at its ends, where the package is located below the base when the end-of-arm tool is in a clamping orientation. A gripping tool is movably mounted above the base, the gripping tool having first and second gripping members movable toward each other to grip a cardboard sheet between the gripping members and movable away from each other to release a cardboard sheet gripped between the gripping members. The gripping tool is mounted for linear movement to and from a retracted position located substantially within the profile of the end-of-arm tool and an extended position in which at least a portion of the gripping members extends outside the profile of the end-of-arm tool, where the profile of the end-of-arm tool is defined by the horizontally outermost extents of the base and the clamping members when the end-of-arm tool is in the clamping orientation. The end-of-arm tool is adapted to be mounted to a robotic arm for movement to and from the clamping orientation and a sheet placing orientation. When the end-of-arm tool is in the cardboard sheet placing orientation and the gripping tool is in the extended position, the at least a portion of the gripping members extends downwardly below the base and the clamping members, and the gripping tool is adapted to grip a substantially vertically oriented cardboard sheet that is located substantially entirely below the base and the clamping members.

In one embodiment, the end-of-arm tool is configured to be moved from the clamping orientation to the sheet placing orientation and from the sheet placing orientation to the clamping orientation by rotating the end-of-arm tool approximately 90 degrees about a substantially horizontal axis.

In yet another aspect of the invention, a method of packing a package into an egg-carton container is provided. According to the method, an end-of-arm tool as generally described above is mounted to a robotic arm operable to move and manipulate the tool. The robotic arm is operated to move the end-of-arm tool so that a package is located between the clamping members, and the linear thrusters are extended to clamp the package between the clamping members. Then, the robotic arm is operated to move the end-of-arm tool to move the clamped package proximate to a desired location in the package container. When the package is at or just above the desired location, the linear thrusters are retracted to permit the clamping members to pivot apart from each other to release the package and place the package in the desired location.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a detailed top view of the end of arm tool;

FIG. 2 is a front elevation view of the end of arm tool;

FIG. 3 is a side elevation view of the end of arm tool;

FIG. 4 is a side elevation view of a clamp finger;

FIG. 5 is a front elevation view of a clamp finger;

FIG. 6 is a side elevation view of a robotic arm having attached thereto an end of arm tool;

FIG. 7 is front elevation view of the end of arm tool holding three 12-egg cartons;

FIG. 8 is a front elevation view of the end of arm tool holding two 18-egg cartons;

FIG. 9 is a front elevation view of another embodiment of the end of arm tool;

FIG. 10 is a top perspective view of another embodiment of the end of arm tool;

FIG. 11 is a detailed top view of the embodiment shown in FIG. 10;

FIG. 12 is a side illustration of the embodiment shown in FIG. 10 holding three 12-egg cartons;

FIG. 13 is a side illustration of the embodiment shown in FIG. 10 in an open configuration; and

FIG. 14 is a front illustration of another embodiment of the end of arm tool using a pusher mechanism to release a package into a box.

FIG. 15 is an exploded view of an end of arm tool according the embodiment shown in FIG. 10, attached to a robotic arm and configured for placing a divider sheet.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the figures generally and in particular to FIGS. 1 through 3, there is illustrated an end of arm tool (EOAT) 10 that can place packages containing fragile items in cases. End of arm tool 10 includes a main plate 12 having a top surface 14 and a bottom surface 16. Vacuum cup assemblies 18 are attached to plate 12 at top surface 14 and extend through bottom surface 16. Release actuators 20 are connected to a release actuator mount 22 that is connected to bottom surface 16 of plate 12. A pusher assembly 24 is attached to release actuator 20. Pusher assembly 24 is located substantially parallel to plate 12 below bottom surface 16. Clamp fingers 26 are connected to a clamp bar 28 that is operated by a clamp actuator 30. A clamp actuator bracket 32 attaches clamp actuator 30 to bottom surface 16 of plate 12.

The shape of plate 12 is typically a rectangle as shown. Those skilled in the art will appreciate that the shape and dimensions of plate 12 will depend on the particular application of the end of arm tool. For example, for an end of arm tool that is suitable for packing egg cartons in a shipper case, the dimensions of plate 12 are such that plate 12 will fit within the inner walls of the shipper case and can hold about three 12-egg cartons (six rows by six columns of eggs for a total of 36 eggs) or about two 18-egg cartons (six rows by six columns of eggs for a total of 36 eggs). For example, for such an application plate 12 may be a square having sides from about 9.5 inches to about 11 inches and more preferably from about 10 inches to about 10.5 inches.

As shown in FIG. 1, in the exemplary embodiment there are ten vacuum cup assemblies 18 arranged on plate 12. The number and configuration of vacuum cup assemblies 18 can vary depending on parameters such as the size, shape and weight of the items to be packed. The arrangement of vacuum cups 18 shown in FIG. 1 is designed to pick up three 12-egg cartons or two 18-egg cartons, as best seen in FIGS. 7 and 8.

Clamp fingers 26 are typically configured in pairs. In the exemplary embodiment shown there are five pairs of clamp fingers 26. Again, this arrangement is suitable for grasping the ends of three 12-egg cartons or two 18-egg cartons (see FIGS. 7 and 8), and the number and arrangement of clamp fingers 26 may be varied to suit the size and shape of the items to be packed. Each clamp finger 26 of a pair is attached to a corresponding clamp bar 28. Clamp bars 28 are located opposite each other substantially parallel to the front and back edge of plate 12. Each clamp bar 28 is operated by a pair of clamp actuators 30. Each clamp actuator 30 is attached to bottom surface 16 by a bracket 32. Clamp actuators 30 are preferably linear thrusters, but may also be pneumatic cylinders, hydraulic cylinders, or other similar devices known to those skilled in the art. Clamp fingers 26 are movable between two positions as shown in FIG. 3 (with the extended or open position shown in dashed lines).

Release actuators 20 are provided to operate pusher assembly 24. Release actuators 20 are preferably linear thrusters, but may also be pneumatic cylinders, hydraulic cylinders, or other similar devices known to those skilled in the art. Pusher assembly 24 can have any shape and/or form suitable to push on the top surface of the items currently held by clamp fingers 26 to release the items from end of arm tool 10. For example, pusher assembly 24 may be in the form of a pusher plate or one or more pusher bars.

Referring now to FIGS. 4 and 5, each clamp finger 26 has a top section 34, a middle section 36, a bottom section 38, and a fastener hole 40. Each clamp finger 26 attaches to clamp bar 28 at top section 34 by means of a bolt or other fastener which is inserted through fastener hole 40. Bottom section 38 is preferably slightly curved at the tip to provide a hook to clamp onto the edge of the package. Clamp finger 26 is typically made of a suitable flexible material such as spring steel. Because clamp finger 26 is both thin and flexible, it slips easily between a carton and the inner wall of a case, and may be easily withdrawn after the carton is placed in the case.

FIG. 6 illustrates a robotic arm 50 having attached thereto an end of arm tool 10. End of arm tool 10 is attached to the face plate 52 of robotic arm 50. FIG. 7 shows end of arm tool 10 lifting three 12-egg cartons, and FIG. 8 shows end of arm tool 10 lifting two 18-egg cartons. In FIGS. 7 and 8, the vacuum cups are seen in contact with the top surfaces of the egg cartons, and the clamp fingers are shown clamping the ends of the egg cartons.

More generally, end of arm tool 10 comprises a plate having a top surface and a bottom surface as previously described, gripping means attached to the bottom surface of the plate to grip the top surface of a package, and clamping means attached to the bottom surface of the plate to clamp the ends of a package. The gripping means may be any suitable device capable of engaging the top surface of the package and lifting the package, including, without limitation, the vacuum cup assembly described above and other such devices known to those skilled in the art. The clamping means may include any suitable device capable of holding the package together to prevent it from becoming open as the package is lifted by the robotic arm. Suitable clamping means include, without limitation, the clamp fingers connected to the clamp bar which is operated by the retractable means. The retractable means may include any suitable device capable of extending and retracting the clamp bar such as clamp actuators as described above and other such devices known to those skilled in the art.

The end of arm tool is preferably also provided with releasing means attached to the bottom surface of the plate to release the clamping means from the edges of the package. The releasing means can include any suitable device capable of disengaging the package from the end of arm tool. Examples of suitable releasing means include, without limitation, the vacuum cup assembly previously described wherein the air pressure can be reversed to “blow off” the package from the gripping means, a pusher assembly operated by pushing means, any other devices known to those skilled in the art, and combinations thereof. As used herein, the term “blow off” refers to applying positive air pressure such that the package becomes disengaged from the vacuum cup assemblies. The pushing means can include any suitable device capable of moving the pushing assembly below the ends of the clamp fingers. Suitable pushing means include, without limitation, release actuators as described above and other similar devices known to those skilled in the art. It will be apparent to those skilled in the art that the package can remain attached to the end of arm tool apparatus at the clamping means even though the package has been disengaged from the gripping means. The releasing means can include the combined operation of the vacuum cup assembly and the pusher assembly as previously described.

The method of the invention is performed by connecting an end of arm tool as described above to a robotic arm, and controlling the robotic arm to place the end of arm tool over a package so that the vacuum cup assembly makes contact with the top surface of the package. Next, a vacuum is generated so that the vacuum cup assembly grips the top surface of the package. Some packages such as egg cartons can become open in some instances when lifted by their tops, resulting in the undesired spillage of the contents of the packages (i.e., eggs). To prevent this undesired spillage, the method further comprises retracting the clamp fingers to clamp the edges of the package. In a preferred embodiment of the present invention, the clamp fingers are placed in a manner such that the bottom-most part of the package can be grasped. The method further comprises controlling the robotic arm to lift the package and carry the package to a case, moving the robotic arm into the case to place the package in the case, releasing the package, and moving the robotic arm out of the case.

Releasing the package is preferably performed by reversing the air pressure in the vacuum cup assemblies to “blow off” the package from the vacuum cup assemblies, and/or by operating a pusher assembly to push the package off the clamp fingers to completely release the package from the end of arm tool.

In an alternative embodiment, clamp fingers may be provided on all four sides of the main plate in order to clamp the packages on their sides as well as their ends. This provides additional protection against inadvertent opening of the cartons when they are picked up. As shown in FIG. 9, side clamp fingers 60 and end clamp fingers 62 are mounted on the sides and ends of main plate 64, respectively. Side clamp fingers 60 and end clamp fingers 62 may be separate and individual, as described above and shown in FIGS. 1 through 8, or may be formed as a unitary piece of material as is the case with side clamp fingers 60 shown in FIG. 9. The material is thin and flexible, such as 0.965 mm stainless steel.

In some applications, it is desirable to place a cardboard divider or slip sheet between columns of cartons in the shipper case. To automate the placement of the divider, a gripper 66 is provided. As shown in FIG. 9, gripper 66 includes a pair of gripper fingers 68. Gripper 66 is mounted on and moves laterally along gripper slide 70. Gripper 66 is operated by gripper actuator 72 which is attached to main plate 64 via gripper actuator bracket 74.

In operation, gripper 66 is moved outward along gripper slide 70 so as to extend beyond the edge of plate 64. Gripper fingers 68 are opened to pick up a single sheet of cardboard from a sheet feeder device (not shown). Gripper fingers 68 are then closed to grasp the sheet, and the robotic arm to which the end of arm tool is attached is operated to position the sheet in the case, whereupon gripper fingers 68 are opened to release the sheet in the desired position. Gripper 66 is then moved back along gripper slide 70 to its normal position. Gripper actuator 72 is preferably a linear thruster, but may also be a pneumatic cylinder, hydraulic cylinder, or other similar device.

Another alternative embodiment of the invention is illustrated and described herein with reference to FIGS. 10-15. In this embodiment, a pivotal-clamp end of arm tool 80 includes pivotal clamps 82 pivotally mounted to a main plate 83 by hinges 84. Each clamp 82 includes chamfered corners 86, which are beneficial for avoiding snags with box flaps when tool 80 is inserted into a box for loading, and a retention lip 88 for retaining a clamped side of an egg carton. With reference to FIG. 12, linear thrusters 90 for closing clamps 82 to clamp the ends and side edges of an egg carton E include thruster pads 92 and are mounted to the underside of a thruster mounting plate 94. While the embodiment illustrated in FIGS. 10-13 and 15 includes four clamps 82, in should be noted that an end-of-arm tool may include only two pivotal clamps for clamping only the ends or sides of an egg carton, within the scope of the invention. Thruster mounting plate 94 is attached to a main riser 96 above a main plate 83 in generally parallel, spaced-apart relation to main plate 83. Return springs 100 are connected at one end below thruster mounting plate 94 and at the other end to hinges 84 at points above the pivotal axes of clamps 82.

According to one method of use, a robotic arm is operated to locate tool 80 just above egg cartons E to be clamped and moved, with one pair of clamp members 82 flanking the ends and another pair of clamp members 82 flanking the side edges of egg cartons E as illustrated in FIG. 13. The clamp 82 in the foreground, oriented for clamping the front end of egg cartons E, is illustrated in phantom lines to reveal components that would otherwise be hidden behind it. In the illustrated orientation of tool 80, thrusters 90 are in a retracted orientation in which thruster pads 92 have receded to permit springs 100 to pull the top portions of clamps 82 inward toward main riser 96, thus causing the bottom ends of clamps 82 to pivot outwardly to an open orientation for receiving egg cartons E to be clamped. The robotic arm is then operated to lower tool 80 to a position in which a bottom of main plate 83 gently abuts the tops of egg cartons E, and linear thrusters 90 are extended in the direction indicated by arrows A to push thruster pads 92 outwardly against clamps 82, thus causing the bottom ends of clamps 82 to pivot inwardly in the direction indicated by arrows C to clamp the ends and side edges of egg cartons E, as illustrated in FIG. 12. Once egg cartons E are clamped, the robotic arm is operated to move egg cartons E to a desired location, and thrusters 90 are retracted to permit springs 100 to open clamps 82 as described above, thereby releasing egg cartons E and placing them in the desired location.

Because vacuum cups or other suction means are preferably omitted from the present embodiment, it will be noted that a pusher assembly for releasing egg cartons E as described with respect to the previous embodiments is not strictly necessary; rather, egg cartons E may be released simply by opening clamps 82. However, pusher assemblies 102 may be advantageously included in tool 80 to assist in releasing egg cartons E when clamps 82 are prevented or restrained from being fully opened. For example, as illustrated in FIG. 14 for a two-clamp embodiment of tool 80, an egg carton packing box B may be scarcely wider than tool 80 itself, so that when thrusters 90 are retracted, thruster pads 92 recede inwardly and lose contact with clamps 82, while the full opening of clamps 82 by springs 100 is obstructed by the lower portions of clamps 82 impinging interior side walls of box B, which may result in some flexion of clamps 82 as illustrated. Due to the obstruction in the illustrated case, clamps 82 are not opened wide enough to permit egg carton E to pass between the ends of retention lips 88 under the force of its own weight. In such cases, it is beneficial for tool 80 to include pusher assemblies 102 to apply a sufficient downward force to the top of egg carton E, as indicated by arrows P, so that egg carton E may pass between retention lips 88 to be released from clamps 82 as tool 80 is lifted vertically out of box B by a robotic arm (not shown) in the direction indicated by arrow D. To force egg carton E through a space that is narrower than the length of egg carton E, the downward force provided by pusher assemblies 102 may cause the ends of egg carton E, the ends of retention lips 88, or both to flex or deflect somewhat. As shown, pusher assemblies 102 include pusher cylinders 104 and push rods 106 for applying the releasing force to egg cartons E, but any suitable pushing means may be employed.

Pivotal-clamp end of arm tool 80 optionally includes divider dispenser gripping assembly 108, similar to gripper 66 and its associated components described above. With reference to FIGS. 12 and 13, gripping assembly 108 includes a divider sheet gripper 110 with fingers 112 adapted to be moved toward and apart from each other to grip and release a divider sheet, which may be a typical cardboard divider sheet as commonly used in egg packaging. Gripper 110 is slidably mounted to the top of thruster mounting plate 94 by gripper slide 114. As illustrated in FIGS. 12 and 13, the usual position of gripper 110 is a retracted position in which no part of gripper 110 extends horizontally beyond the profile of tool 80, thus avoiding impingement of a packing box or other environmental obstruction by gripper 110 while tool 80 is moved by a robotic arm in its upright orientation for egg carton clamping, shown in the figures.

Turning to FIGS. 12 and 15, the operation of gripper 110 is illustrated. When it is desired to place a divider sheet in a packing box, which may be a cardboard divider sheet D as shown in the figure, gripper 110 is moved linearly along gripper slide 114 in the direction indicated in FIG. 12 by arrow B. In the extended position of gripper 110 and gripper fingers 112, shown in FIG. 12 in dashed lines and indicated as 110′ and 112′, respectively, gripper fingers 112 extend outside the profile of tool 80, and gripper 110 may grip sheet D without sheet D impinging other components of tool 80, as shown in FIG. 15. For placement of sheet D, tool 80 is rotated into a position in which fingers 112 point downward for holding sheet D in a vertical orientation. This step may be performed before sheet D is gripped, as when a sheet feeder (not shown) provides sheet D already in a vertical orientation, or after sheet D is gripped, as when a sheet feeder (not shown) provides sheet D in a horizontal orientation. A robotic arm articulating member 116 and pivoting head 118 are shown exploded from tool 80, for purposes of illustrating one manner in which a robotic arm may reorient tool 80. In particular, tool 80 may attach to pivoting head 118, and pivoting head 118 may carry out the movement of tool 80 to and from its usual clamping orientation and the sheet placement orientation by rotating with respect to articulating member 116 about a horizontal axis, as indicated by arrow R. Once sheet D is gripped and tool 80 is in the sheet placement orientation, the robotic arm moves tool 80 to move sheet D to a desired location, and fingers 112 are separated to release and place sheet D.

Example

An end of arm tool according to the invention was constructed for case packing of 36 eggs in either three 1-dozen cartons or two 1.5-dozen cartons. The end of arm tool was specifically designed to pick up plastic foam cartons off an in-feed conveyor and place them into one of three different shipper cases for shipment to grocery stores. The space utilized in the shipper cases is the same for either the three 1-dozen cartons or the two 1.5-dozen cartons. The three shipper cases sizes and configurations are as follows: (1) 15 dozen case—3 dozen per layer, 5 layers; (2) 24 dozen case—6 dozen per layer, 4 layers; and (3) 30 dozen case—6 dozen per layer, 5 layers. Shipper case sizes and dimensions may change from time to time, but do not alter the operation of the end of arm tool. The controller for the robotic arm may simply be reprogrammed for the different cases.

The EOAT was attached to the face plate of, and operated by, a Model M-6iB/6s six-axis robotic arm supplied by FANUC Robotics America, Inc. (Rochester Hills, Mich.). The structure, operation, programming and control of the robotic arm are well known in the art, and thus will not be described in detail herein. The mechanisms on the end of arm tool (i.e., clamp actuators, release actuators, gripper actuator) may be pneumatically actuated by electrically-operated pneumatic solenoids, which are remotely mounted. Commercial robotic arms provide the necessary electrical and pneumatic connections for the end of arm tool.

The end of arm tool included a substantially square plate measuring about 10.13 inches on each side. The plate was made of a one-quarter inch thick polycarbonate material. Ten vacuum cup assemblies were attached to the plate such that the vacuum cups were located on the bottom surface of the plate. A release actuator was mounted at each of the four corners of the plate using four release actuator mounts attached to the bottom surface of the plate. A pusher assembly was connected to the four release actuators. The pusher assembly comprised two outer bars and one inner bar. The two outer bars were connected each to two release actuators. In addition, there were two linking bars that connected the two outer bars to each other. The inner bar was attached to the linking bars between the two outer bars. The end of arm tool further comprised two clamp bars. Each clamp bar was connected to two clamp actuators. The clamp actuators were attached to the bottom surface of the plate using clamp actuator brackets. Five clamp fingers that were made of 0.0625 inch thick spring steel were attached to each clamp bar. The middle section of each clamp finger was approximately 3.23 inches long, and its curved bottom section formed a hook about 0.19 inches long with a radius of 0.12. These dimensions are suitable for gripping standard egg cartons.

A shipper case was packed with egg cartons using the end of arm tool described above. The end of arm tool was placed over the egg cartons by the robotic arm, i.e., centered directly over three 12-egg cartons or two 18-egg cartons, so that the vacuum cup assemblies made contact with the top surface of each egg carton. A pneumatic solenoid was actuated which pressurized a vacuum generator. The vacuum was supplied to the vacuum cup assemblies causing the vacuum cups to grip the top surface of each egg carton. After a short delay of about 0.5 seconds, the clamp fingers were retracted via the pneumatic clamp actuators and clamp bars so that the curved tips of the clamp fingers hooked underneath the center lip of the ends of the lower portions of the egg cartons. The clamp actuators were actuated to keep the clamp fingers normally extended. The open and closed positions of the clamp fingers may be seen in FIG. 3 (open position shown in dashed lines). The clamp fingers were used to prevent the egg cartons from becoming open as they were lifted by the vacuum cup assemblies.

After another short delay of about 0.5 seconds, the robotic arm lifted the egg cartons and moved them into the shipper case. As noted above, the clamp fingers used were made of spring steel so that the clamp fingers hooked to the edge of the egg cartons could easily fit in the narrow gap between the inside surface of the shipper case and the egg cartons without damaging either the egg cartons or shipper case. The robotic arm placed the egg cartons at the proper height location, depending on the layer count of the shipper case. Once in position, the vacuum solenoid was actuated to turn off the vacuum, and the air pressure was reversed to supply a positive air pressure to assist in releasing the vacuum cups from the tops of the egg cartons, i.e., to “blow off” the tops of the egg cartons. The clamp actuators were actuated causing them to extend and to move the clamp fingers to the open position. The inner surfaces of the shipper case normally prevent the fingers from opening sufficiently for the clamp fingers to completely release the egg cartons. Thus, the pusher assembly was used to force the egg cartons off the clamp fingers. Once the air pressure was reversed to the blow off mode and the clamp fingers were extended, the robotic arm moved up approximately one-half inch. The cartons had a tendency to come up with the robotic arm. The pusher assembly was actuated by a pneumatic solenoid that pressurized the release actuators so that they extended and pushed the pusher assembly downward, thus releasing the egg cartons from the clamp fingers. The normal state of the release actuators is retracted, that is, pusher assembly up.

After another short delay of approximately 0.5 seconds, the robotic arm moved the end of arm tool up and out of the shipper case, the “blow off” air was turned off and the pusher assembly was retracted to its normal position. The cycle was completed, and it was repeated until the shipper case was filled with egg cartons.

In an alternate method of operation, two layers of egg cartons were placed on one side of a shipper case as described above. The robotic arm was then moved to a cardboard sheet dispenser, and the gripper was operated to pick up a single sheet of cardboard from the dispenser by opening the gripper fingers, placing them over the end of the sheet, and closing them to grip the sheet. The robotic arm was operated to pull out the sheet, move it up and over the shipper case, orient it vertically, slip it into place in the case, and release it adjacent the egg cartons in the case. The arm was then operated as described above to fill the remaining space in the case with more egg cartons. As a result, the cardboard sheet was positioned as a vertical divider between columns of cartons. Of course, in other applications, a divider could be placed horizontally between layers of cartons if desired.

While the invention has been described with respect to certain preferred embodiments, as will be appreciated by those skilled in the art, it is to be understood that the invention is capable of numerous changes, modifications and rearrangements and such changes, modifications and rearrangements are intended to be covered by the following claims. 

1. An end of arm tool comprising: first and second generally opposed clamping members pivotally connected to a base about a first clamping axis and a second clamping axis, respectively, the first and second clamping axes being generally parallel to each other; and first and second linear thrusters mounted for linear movement relative to the base, the thrusters having contact ends configured to extend toward and press against contact surfaces of the first and second clamping members, respectively, to cause a clamping end of each of the first and second clamping members to pivot generally towards the clamping end of the other of the first and second clamping members, and to produce a clamping force for clamping a package between the first and second clamping ends.
 2. The tool of claim 1, further comprising a pusher mechanism adapted to push a package away from the clamping members in a direction transverse to a distance between the clamping members to release the package from the clamping members when the clamping members partially obstruct the movement of the package away from the clamping members.
 3. The tool of claim 2, wherein the clamping members comprise retention lips adjacent their clamping ends, the retention lips being a portion of each clamping member turned inwardly toward the opposed clamping member, wherein a distance between the retention lips is shorter than a distance between the ends of the partially obstructed package, and wherein the pusher mechanism is adapted to push the partially obstructed package in the direction transverse to the distance between the retention lips with sufficient force to cause at least one of the package and the clamping members to be deflected and to permit the clamped package to pass between the retention lips and away from the clamping members.
 4. The tool of claim 1, wherein the contact ends of the thrusters include generally convex, curved contact faces configured for sliding contact with the contact surfaces of the clamping members.
 5. The tool of claim 1, further comprising: first and second return springs configured to urge the contact surfaces of the first and second clamping members, respectively, to pivot toward and against the contact ends of the first and second thrusters, respectively, and to urge the first and second clamping ends apart from each other.
 6. The tool of claim 1, further comprising: third and fourth generally opposed clamping members pivotally connected to the base about a third clamping axis and a fourth clamping axis, respectively, the third and fourth clamping axes being generally parallel to each other and generally orthogonal to the first and second clamping axes; and third and fourth linear thrusters mounted for linear movement relative to the base, the thrusters having contact ends configured to extend toward and press against contact surfaces of the third and fourth clamping members, respectively, to cause a clamping end of each of the third and fourth clamping members to pivot generally towards the clamping end of the other of the third and fourth clamping members, and to produce a clamping force for clamping a package between the third and fourth clamping ends; wherein the first, second, third and fourth clamping members are configured to clamp a group of adjacent packages simultaneously between the first and second clamping members and between the third and fourth clamping members.
 7. An end of arm tool comprising: first and second clamping members movably mounted to generally opposite sides of a base for movement of generally opposed clamping portions of the first and second clamping members toward each other and into a clamping configuration for clamping a package between the clamping portions and movement of the clamping portions away from each other and out of the clamping configuration to release a package clamped between the clamping portions, wherein the clamping members are adapted to clamp a horizontally oriented package at its ends, where the package is located below the base when the end-of-arm tool is in a clamping orientation; and a gripping tool movably mounted above the base, the gripping tool having first and second gripping members movable toward each other to grip a cardboard sheet between the gripping members and movable away from each other to release a cardboard sheet gripped between the gripping members; wherein the end-of-arm tool has a profile defined by the horizontally outermost extents of the base and the clamping members when the end-of-arm tool is in the clamping orientation, wherein the end-of-arm tool is adapted to be mounted to a robotic arm for movement to and from the clamping orientation and a sheet placing orientation, wherein the gripping tool is mounted for linear movement to and from a retracted position located substantially within the profile of the end-of-arm tool and an extended position in which at least a portion of the gripping members extends outside the profile of the end-of-arm tool, and wherein, when the end-of-arm tool is in the cardboard sheet placing orientation and the gripping tool is in the extended position, the at least a portion of the gripping members extends downwardly below the base and the clamping members, and the gripping tool is adapted to grip a substantially vertically oriented cardboard sheet that is located substantially entirely below the base and the clamping members.
 8. The end-of-arm tool of claim 7, wherein the end-of-arm tool is configured to be moved from the clamping orientation to the sheet placing orientation and from the sheet placing orientation to the clamping orientation by rotating the end-of-arm tool approximately 90 degrees about a substantially horizontal axis.
 9. A method of packing a package into a case, the method comprising: providing an end-of-arm tool mounted to a robotic arm, the end-of-arm tool comprising first and second generally opposed clamping members pivotally connected to a base about a first clamping axis and a second clamping axis, respectively, the first and second clamping axes being generally parallel to each other, and first and second linear thrusters mounted for linear movement relative to the base, the thrusters having contact ends configured to extend toward and press against contact surfaces of the first and second clamping members, respectively, to cause a clamping end of each of the first and second clamping members to pivot generally towards the clamping end of the other of the first and second clamping members, and to produce a clamping force for clamping a package between the first and second clamping ends; operating the robotic arm to move the end-of-arm tool so that a package is located between the clamping members; extending the linear thrusters to clamp the package between the clamping members; operating the robotic arm to move the end-of-arm tool to move the package proximate to a desired location in the case; and retracting the linear thrusters and permitting the clamping members to pivot apart from each other to release the package and place the package in the desired location. 